Vacuum tube



April 17, 1928.

A. H. JAHN VACUUM TUBE Filed Ma 27. 1926 ATTORNEYS 2 Sheets-Sheet 1WITNESSES April 17, 1928.

A. H. JAHN VACUUM TUBE Filed May 2'7. 1926 2 Sheets-Sheet 2 lNVENTORATTORNEYS Patented Apr. 17, 1928.

AUGUSTUS HENRY J'AHN, OI PITTSBURGH, PINNBYLVANIA.

VACUUM TUBE.

Application filed Kay 27,

This invention relates to improvements in electron emission devicescommonly known as vacuum tubes, and'the object thereof be iug to connectelectro-inagnetic code with the grid and plate elements to set' upelectro magnetic fields in addition to that of a permanent magnet forthe purpose of assisting the action of the grid and p ate.

Other objects and advantages of the invention will appear in thefollowing specification, reference bein had to the accompanying drawingin w ich:

Figure 1 is a. side elevation of the improved vacuum tube.

Figure 2 is a plan view thereof.

Figure 3 is an inverted plan vlew of the base. Figure 4 is a diagramillustrating the improved tube in a typical receiving circuit.

In carrying out the invention, provision is made of a. glass bulb 1 fromwhich the 111! is exhausted during manufacture according to well knownpractice. The bulb 1 is suitably mounted upon a base 2 which has fourprojecting prongs 3, 4, 5 and 6 toengage the contacts of a suitablemounting. These prongs in the order given represent the positivefilament lead 3 (Fig. 4), the negative filament lead 4, the grid lead 5(Fig. 4), and the plate lead 6.

Only a brief reference is required to identify the diagram in Fig. 4 asbeing largely of conventional nature. Use is made of the customar A andB batteries and a O battery may a so be employed as shown if desired.The improved vacuum tube is here shown as situated in the detectingstage of a radio receiver, and any additional stages added at the rightwill employ a similar tube. The improved tube is capable of use otherthan that of a detecto because it is capable of greatly amplifying theelectrical signal impulses impressed thereupon. The wiring diagram inFigure 4 is mainly intended to show how the tube is situated in theconventional receiving circuit, and further specific reference to thereceiving system or hook-up will not be necessary.

Situated within the bulb 1 is a permanent electro-magnet 7. This magnetis of familiar horse-shoe or U-shape. It is mounted in any suitablemanner, a glass pedestal 8 being shown in order to disclose some kind ofmounting. The magnet has north and south pole pieces 9 and 10 disposedin confronting positions and these may either be spective north andsouth 1926. Serial No. 118,084.

made integrally with the yoke of the magnet or magO consist of soft ironmembers riveted or lted in position.

Co ls 11 and 12 are wound upon the respectlve pole pieces 9 and 10 indirectionsto produce electro-magnetic fields agreeing with the field ofthe permanent magnet 7, when current is conducted through said coils.One end of the coil 12 is connected with the lead 5" (Fig. 4) the otherend being connected with the grid 13. The coil 12 is thereforeinterposed in the grid circuit. One end of the coil 11 is connected withthe leadfi, the other end being connected with the plate 14. The coil 11is therefore interposed in the plate circuit. Electrical current flowingthrough the respective coils will serve the purpose of strengthening there poles of the permanent magnet 7 before being impressed upon eitherthe plate 14 or rid 13.

The operation is as fol ows. The permanent magnet 7 produces an even oruniform magnetic flux or. field when uninterrupted by externalinfluences. The plate 14 assumes a position in front of the north pole.The gr1d 13 is interposed between the filament 15 and the plate 14, butthe grid is disposed near the south pole 10. The plate 14, is thereforeof positive potential while the grid 13 is of negative otential, but thepositive potential of the p ate 14 is increased by virtue of the factthat it is connected with the positive pole of the B-battery, andnegative potential of grid 13 is increased by virtue of the fact that itis disposed near and in the negative magnetic flux of south pole.

Assume that an incoming signal impulse reaches the lead 5 (Fig. 4). Thesignal impulse passes on to the coil 12 producing a rise of theelectromagnetic field of the permanent magnet dependin upon the strengthof the incoming signa impulse and the consequent superimposedelectromagnetic field of the coil 12. The increase or rise of themagnetic flux will affect the grid 13, increasing the negative potentialthereof as the strength of the signal impulse increases.

The grid therefore becomes a more potent factor in controlling thethermionic stream of the filament 15 so that electrons are released in agreater volume with the result that louder and clearer signals can .begot without distortion.

While the construction and arrangement of the improved vacuum tube isthat of a enerally preferred form, obviously modi cations and changesmay be made without departing from the spirit of the invention or thescope of the claims.

I claim y 1. A device of the character described comprising a plate, afilament, a grid interposed between the filament and plate, a permanentmagnet roducing a ma' netic field in which the ate, filament and gridare situated, and a winding upon the south pole of said magnet connectedwith the grld for varying said field as the electrical 1mpulses valthereb producing1 changes in the potentlal of t e grid an a winding 7upon the north pole of said magnet conas electrical impulses vary byvary the nected to the plate for varying said field t iere )y producingchanges in potential of the plate.

2. A device of the character described comprising means for producing aperma-' nent magnetic field, a filament situated in said field forproducing a thermionic stream, a plate constituting a target by whichsaid stream is intercepted, a grid interposed between the filament andplate, and electrodemagnetic means connected with the grid beingoperable by varying electrical im ulses to superimpose anelectro-magnetic fie (lupon said permanent magnetic field andtherctential of the grid to variably ow of said stream.

AUGUSTUS H. JAHN.

control the

